Notch Filter Coating on Laser Diode Facet for Wearable HUD
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Solution Overview
Problem
Wearable heads-up displays face challenges in minimizing bulk while maintaining high visual quality and aesthetic appeal, as existing designs often rely on bulky external components like volume Bragg gratings for narrow waveband laser diodes.
Innovation Solution
Integration of a notch filter coating with a rugate device on the laser diode's facets to achieve a narrow waveband output without the need for external cavities, ensuring high reflectivity within a specific waveband and low reflectivity outside of it, thereby reducing display aberrations and enhancing aesthetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external cavity solutions like volume Bragg gratings are used to achieve narrow waveband laser diodes, then display quality is improved, but device bulk and complexity increase
Solution Approach 1:
The patent combines the laser cavity and notch filter into a single integrated structure. The notch filter coating is applied directly to the laser diode facet, merging two previously separate components (laser cavity and external cavity filter) into one unified device. This integration eliminates the need for separate external cavity components like volume Bragg gratings, thereby reducing device bulk while maintaining narrow waveband output for high display quality
Solution Approach 2:
The notch filter coating is nested within the laser diode structure itself, specifically on the facet surface. This nesting approach places the filtering function inside the laser diode component rather than requiring external placement, effectively reducing the overall device volume while preserving the narrow waveband laser output necessary for high-quality display performance
2Manufacturing precision
If external cavity solutions are used for narrow waveband laser diodes, then display quality is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the laser generation function and the wavelength filtering function into a single integrated component. By applying the notch filter coating directly to the laser diode facet, the system eliminates multiple separate components (laser diode, external cavity, volume Bragg grating), thereby reducing device complexity and assembly requirements while maintaining the narrow waveband output necessary for high display quality
Solution Approach 2:
The laser diode facet serves multiple functions simultaneously: it acts as both the laser output surface and the notch filter medium. This multi-functionality eliminates the need for separate filtering components, reducing overall device complexity while achieving the narrow waveband laser output required for high-quality display performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for compact, high-quality laser diodes that reduce display aberrations and enhance aesthetic appeal by narrowing the waveband output, improving display quality without adding bulk, and is more cost-effective than external cavity solutions.
Implementation Method 1
at least one notch filter coating applied to at least one of the reflective rear facet and the partially reflective output facet. The at least one notch filter coating may be at least partially reflective of light within a narrow waveband and substantially transmissive of light outside of the narrow waveband.
Implementation Method 2
The at least one notch filter coating may include a rugate device.
Implementation Method 3
a reflective rear facet at a first end of the layer of optically active material; a partially reflective output facet at a second end of the layer of optically active material, the second end opposite the first end across a length of the layer of optically active material to define a laser cavity
Implementation Method 4
a layer of optically active material disposed between the layer of p-type semiconductor material and the layer of n-type semiconductor material
Implementation Method 5
a layer of p-type semiconductor material; a layer of n-type semiconductor material; a layer of optically active material disposed between the layer of p-type semiconductor material and the layer of n-type semiconductor material
Data Source
AI summary
Systems, devices, and methods for narrow waveband laser diodes are described. The conventional coating on the output facet of a laser diode is replaced with a notch filter coating that is reflective of wavelengths within a narrow waveband around the nominal output wavelength of the laser diode and transmissive of other wavelengths. The notch filter coating ensures the laser diode will lase at the nominal wavelength and not lase for wavelengths outside of the narrow waveband. The notch-filtered laser diode provides a narrow waveband output that is matched to the playback wavelength of at least one hologram in a transparent combiner of a wearable heads-up display, and thereby reduces or eliminates display aberrations that can result from wavelength sensitivity of the playback properties of the hologram.